Turbocharged and supercharged engines may be configured to compress ambient air entering the engine in order to increase power. Compression of the air may cause an increase in air temperature, thus, an intercooler or charge air cooler (CAC) may be utilized to cool the heated air thereby increasing its density and further increasing the potential power of the engine. Condensate may form in the CAC when the ambient air temperature decreases, or during humid or rainy weather conditions, where the intake air is cooled below the water dew point. Condensate may collect at the bottom of the CAC, or in the internal passages, and cooling turbulators. When torque is increased, such as during acceleration, increased mass air flow may strip the condensate from the CAC, drawing it into the engine and increasing the likelihood of engine misfire and combustion instability.
One approach to address condensate formation in the CAC may involve draining condensate from the CAC to the intake manifold of the engine. However, this method may decrease boost pressure to the engine, thereby reducing engine performance.
In one example, the issues described above may be addressed by a method for draining condensate from a CAC in response to a compressor bypass valve event. Specifically, a drain valve positioned in the CAC may be opened before and/or during the compressor bypass valve event. In one example, the drain valve may be opened in response to opening the compressor bypass valve. In another example, the drain valve may be opened in response to a potential compressor surge event. The potential compressor surge event may be indicated by one or more of a throttle inlet pressure greater than a threshold pressure and a tip-out. Further, before and/or during the compressor bypass valve event, condensate may be drained from the CAC to an alternate location in the engine system. Then, after a duration, the CAC drain valve may be closed. In one example, the duration may be based on a required decrease in pressure at an outlet of the CAC during the compressor bypass valve event.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.